I ran into a problem that wasn’t well documented on the forums, and am (again) writing a blog post for my own later edification.
When you open Audacity it enumeates all the ALSA devices on the system. One of the steps it takes is to enumerate Bluetooth audio devices (to support recording from Bluetooth headsets). If Bluetooth is enabled and there’s a bluetooth audio device that the system cannot connect to, Audacity will hang for an arbitrary period of time (long).
The easiest fix is to temporarily disable Bluetooth when working in Audacity. I’ll post any further developments here if there are any.